5 Joint output of individuals, regions, or nations will be maximized when goods are exchanged between parties in accordance with the law of comparative advantage. This law states that parties will specialize in the production of goods for which they are low opportunity cost producers and exchange these for goods for which they are high opportunity cost producers. Pursuit of personal gain will motivate people to specialize in those things that they do best (that is, for which they are low opportunity cost producers) and sell their products or services for goods for which they are high opportunity cost producers.